The disclosures herein relate generally to computer systems and more particularly to backlit keyboards for portable computer systems.
Portable computer systems are often used in low light situations. In these situations, it is very easy to read information shown on the video display. However, it is quite difficult to see the keys of the keyboard. This presents a fairly significant problem for computer users who rely on visually identifying specific keys to achieve adequate typing proficiency.
Various types of illuminated keyboards have been attempted. However, they have provided only limited success. Some of these keyboards use one or more light diffusers that require several discrete light sources to provide uniform lighting across the area of the keyboard. Other types of illuminated keyboards use electroluminescent lighting components that are integral with construction of the keyboard. Because the electro-luminescent lighting and the keyboard components are manufactured as a single assembly, the functionality of the keyboard and the lighting system are dependent on each other. In these types of constructions, issues associated with yield can cause the cost of the keyboard to be prohibitive for use in cost sensitive applications.
U.S. Pat. No. 4,060,703 discloses a sandwich-type computer keyboard with keys characterized by a tactility to provide a positive degree of tactile feedback to an operator and having an electro-luminescent panel for illuminating the keyboard panel. The electro-luminescent panel is disclosed to be an integral portion of the keyboard.
U.S. Pat. No. 4,449,024 discloses a backlit keyboard including a printed circuit board on which is mounted in a central location a single lamp. The single lamp is replaceable from the backside of the board and extends into a clear plastic light diffuser over which an overlay is disposed. A bezel is provided to define key areas in the translucent overlay such that the single lamp disperses light energy through the diffuser to light up the entire overlay. The single lamp is mounted in a socket formed in the printed circuit board.
U.S. Pat. No. 4,489,227 discloses a keyboard having a side-lighted transparent support plane. The support plane includes a plurality of light-pipes vertically projecting therefrom through an overlying foam over-travel pad. A pair of patterned membrane switch layers, separated by a low density foam spacer, overly the over-travel pad and are positioned relative to a plurality of key-caps slidably mounted to the light-pipes.
U.S. Pat. No. 4,670,633 discloses a keyboard capable of illuminating push buttons with a small number of discrete light sources. The light sources are randomly distributed below a grating-like retainer provided for retaining push buttons of the keyboard. Light rays from the light sources are reflected by means of pyramidal reflectors disposed above the light sources.
U.S. Pat. No. 4,806,908 discloses a keyboard having a plurality of keys that are mounted in parallel columns on a key supporting panel. Each key includes a translucent core having a legend on its upper end, a conductor on its lower end, and an opening therethrough intermediate its ends. Each core is mounted for reciprocation at its lower end in a plastic sleeve. An elongated electro-luminescent strip extends through the an opening in each column to prevent accidental withdrawal of the keys, and to illuminate the legends on a column of keys when energized.
Accordingly, there is a need for a backlit keyboard that provides uniform illumination and that has a keyboard portion and an illumination portion that are separately manufactured as functional subassemblies.
One embodiment, accordingly, provides a keyboard having separately manufactured keyboard and illumination subassemblies having individual functionality which is not dependent on the integration of the two subassemblies. To this end, one embodiment provides an illuminated keyboard including a keyboard subassembly having a plurality of key mechanisms mounted on a first side thereof. A light panel having a plurality of openings formed therethrough in a pattern generally corresponding to the plurality of key mechanisms is provided. The light panel is mounted adjacent the first side of the keyboard subassembly with each one of the key mechanisms extending through a respective opening in the light panel. A key cap is attached to each one of the key mechanisms.
A principle advantage of a keyboard according to the embodiments presented herein is that the entire area of the keyboard is more uniformly illuminated than prior attempts at illuminating keyboards.